1. Geomorphic Processes: II. Exogenous
II. Gradation Processes –
Weathering, Mass Wasting, Erosion, Transportation
and Deposition

2. Geomorphic Processes:
Physical processes which create and modify landforms on the surface of the earth
Endogenous (Endogenic) vs.Exogenous (Exogenic) Processes
Rock Cycle 

3. A. Endogenous Processes
Endogenous Processes are large-scale landform building and transforming processes
– they create relief.
1. Igneous Processes
Volcanism: Volcanic eruptions  Volcanoes
Plutonism: Igneous intrusions
Tectonic Processes (Also called Diastrophism)
Folding: anticlines, synclines, mountains
Faulting: rift valleys, graben, escarpments
Lateral Faulting: strike-slip faults
Earthquakes  evidence of present-day tectonic activity

4. B. Exogenous Processes
Also called Gradational Processes, they comprise degradation and aggradation – they modify relief
a continuum of processes – Weathering  Mass Wasting  Erosion  Transportation  Deposition
these processes are carried through by Geomorphic Agents: gravity, flowing water (rivers), moving ice (glaciers), waves and tides (oceans and lakes), wind, plants, organisms, animals and humans
1. Degradation Processes  Also called Denudation Processes
a. Weathering , b. Mass Wasting and c. Erosion and Transportation
Aggradation Processes
a. Deposition – fluvial, eolian, glacial, coastal

5. Degradation Processes: Weathering, Mass Wasting, Erosion and Transportation

6. Relationship: Weathering Mass Wasting Erosion Denudation and
Transportation
Together,
these processes are
responsible for
Denudation
of Earth’s surface

7. WEATHERING Types of Weathering: 1) Physical or Mechanical Weathering,
Weathering is disintegration and decomposition of rocks in situ – no transportation involved  produces regolith
More precisely, it involves the mechanical or physical disintegration and/or chemical decomposition that fragments rock masses into smaller components that amass on-site, before being moved by gravity or transported by other agents
The processes begin in microscopic spaces, cracks, joints, faults, fractures, lava vesicles and other rock cavities
Types of Weathering: 1) Physical or Mechanical Weathering,
2) Chemical Weathering, and 3) Biological Weathering

8. Physical or Mechanical Weathering
Disintegration and decay of rocks via weather elements: high temperatures, extreme cold and freeze-thaw cycles
No change in chemical composition of rocks
Exfoliation – due to thermal expansion/contraction and/or release of pressure when buried rocks are uplifted and exposed
e.g., Exfoliation Dome (Stone Mountain, GA) and Exfoliation Sheets (Sierra Nevada)
Frost Wedging
Salt Wedging

9. Chemical Weathering
 decomposes rocks through a chemical change in its minerals
Oxidation – important in iron-rich
rocks – reddish coloration like rust
Hydrolysis – igneous rocks have
much silica which readily combines
with water
Carbonation and Solution – carbon dioxide dissolved in water reacts with carbonate rocks to create a soluble product (calcium bicarbonate)

10. Biological Weathering
– plants and animals contribute to weathering.
Roots physically break or wedge rock
Lichens (algae and fungi living as single unit), remove minerals and weaken rock by releasing acids
Burrowing animals can increase weathering.
Lichens

11. in the Canadian Rockies
Talus Cones
in the Canadian Rockies
Talus – pieces of rock at bottom of a rock fall
Landslides
Can cause much destruction
A msssive 300-ton boulder blocks
a road in Southern California

12. La Conchita Landslide, January 10, 2005

13. Monterey Park Debris Flow, 1980

14. PCH near Pacific Palisades, November 1956

15. EROSION and TRANSPORTATION
– Various Geomorphic Agents, associated Processes,
and resulting Erosional Features
Flowing Water – Fluvial Morphology
Humid regions:
Perennial streams and entrenched
channels, rapids, waterfalls, plunge
pools, potholes, meandering streams,
bank erosion, oxbow lakes, etc.

16. Wind – Eolian Landscapes
deflation hollows, ventifacts, yardang, etc
Tides and Waves – Coastal Morphology
Sea cliffs, sea caves, sea arches, sea stacks, wave-cut beaches, etc..
Moving Ice – Glacial Morphology
glacial troughs (U-shaped valleys), hanging valleys, glacial lakes,.

17. DEPOSITION
– Various geomorphic agents, associated processes and resulting Depositional Features
Fluvial – Humid regions: Braided streams, sand bars, floodplains (alluvium deposits), natural
levees, distributaries, deltas
Arid regions: Alluvial fans, bajadas,
piedmont alluvial plains, playas,
playa lakes, Salinas (salt flats)
Eolian – Sand dunes (Barchans, Parabolic, Transverse,
Longitudinal, Star), and sand sheets
Coastal – Sea beaches and coral reefs
Glacial – Alpine: Glacial drifts, tills, moraines (lateral, medial, end, terminal, recessional, and ground)
Continental: Till plains, outwash plains, drumlins, eskers, kames, erratic